A conventional tuning fork type, angular velocity sensor has detector plates at the top of two driver plates of the tuning fork type driving part facing in the orthogonal direction. When an angular velocity is applied at a continuous driving state of the driving part, the angular velocity is detected by the output of the detector plates vibrating in opposite direction to each other corresponding to the applied angular velocity.
In an angular velocity sensor in accordance with the prior art, a tightly sealed space is formed by a lid 2, which is made of resin. Lid 2 is attached at an aperture of a case 1, also made of resin, of which one end is open, as shown in FIG. 18.
Inside the tightly sealed space, a circuit board 3 and a metallic weight plate 4 are contained. Supporting pins 5 are attached at four corners inside the case 1 and weight plate 4 and circuit board 3 are elastically supported and fixed by the supporting pins 5. Dampers 6 made of rubber are attached at the four corners of weight plate 4 for the elastic support. Supporting legs 7 made of resin are put between damper 6 and circuit board 3. Supporting pins 5 are crashed at the tips toward the circuit board 3 side after penetrating dampers 6, supporting legs 7 and circuit board 3. Thus, circuit board 3 and weight plate 4 are elastically supported and fixed. A metallic supporting pin 8 is inserted and fixed vertically to weight plate 4, on the circuit board 3 side, as shown in FIG. 19. One end of a metallic, supporting pin 9, is inserted, is fixed to supporting pin 8, and is parallel to weight plate 4. The diameter of supporting pin 9 is about one fifth of the diameter of supporting pin 8. Furthermore supporting pin 9 is made of metallic material having elasticity such as a piano wire, wherein the other end of supporting pin 9 fixed by soldering to a metal plate 10.
One end of each metallic driver plates 11 and 12, facing other across supporting pins 8 and 9, is fixed to each side of metal plate 10. Plate-shaped piezoelectric elements 11a and 12a are fixed on the surfaces of metallic driver plates 11 and 12, respectively. In this way, the tuning fork type driving part is formed. The other ends of driver plates 11 and 12 are twisted orthogonally so that piezoelectric elements 11a and 12a and other plate-shaped piezoelectric elements 13a and 14a are fixed on detector plates 13 and 14, as shown in FIG. 19. In this way, the detector part is formed. A sensor element is composed of the driver part and the detector part.
There is a problem of a usual angular velocity sensor however. Namely, the usual sensor has no ability to judge detected information, drawn to a malfunction of the components, as such, nor the ability to send such information, judged to be a malfunction of the components, to the outside.
The present invention aims to be able to detect, from the outside, the state in which the sensor can not perform a correct detection resulting from partial damage, thereby providing a highly reliable angular velocity sensor.